Voting for coalitions under STV

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Voting for coalitions under STV

• Michael Marsh
• Trinity College Dublin

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Research question

• Under STV voters are asked to rank candidates
• This can also been seen as ranking the parties (
  of those candidates)
• Lower rankings can make a difference to the
  election outcome
• Can votes be seen as a signal of preferred
  government?

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Parties think so

• Parties sometimes do seek to structure choices,
  asking voters to support particular other parties
  with lower preferences
• Parties keeping options option may choose not to
  direct their voters

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BUT

• Strong view that voters at least as attracted to
  candidates as to parties
• 40 plus say main concern is good local candidate
• Almost 40 say they are attracted by candidate
  rather than party and would follow candidate to
  different party
• A Minority vote a straight party ticket

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2002 and 2007

• 2002 FF and PDs, incumbent govt, close, but FG
  and Labour more independent
• 2007 FF and PDs, incumbent govt, expressed pref
  for continued govt, while FG and Lab alternative
  coalition Greens kept options open

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Labour leaflet, Dublin SE
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FG leaflet, Cork SW
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How would we know

• Extensive analysis of transfer patterns from
  aggregate results
• Where do votes of eliminated candidates go?
• Where do surplus votes of elected candidates go?

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Transfers and party cues

• Kennedy (in Representation, 2002) looked at
  transfers and cues 1987-97
• Discovered transfer proportion from party A to
  party B almost 4 times as large when party A/B
  signalled closeness as when they did not

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Transfers in 2007
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Data from exit polls

• Over 3000 cases in both 2002 and 2007
• Coalition prefs untainted by outcome
• Some indication of lower prefs, but vague what
  other parties supported
• Analysis restricted to those expressing just one
  other choice
• Analysis also restricted to constituencies where
  all parties fielded candidates
• N thus 884 and 1467 respectively

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Numbers of parties supported
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FF voters second prefs
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FG voters second prefs
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Labour voters second prefs
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Coalition Preference
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Coalition pref by 1st pref
2002 and 2007 combined
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Effect of coalition preference on preference
votes 2002-7


Coalition Pref

SF odds gt 80
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Effect of coalition preference on first pref
vote, by year
SF145


Coalition Pref
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Effect of coalition preference on second pref
vote, by year
Coalition Pref
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Effect of a coalition preference on second pref
vote, by year and first pref
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(No Transcript)
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Candidate centred voters
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Difference between party and candidate oriented
voters
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Conclusion

• Clear link between vote and coalition preference
• There is a very strong link with first preference
  vote
• There is a link, but not at all so strong for
  second preference votes
• The link varies a lot across parties
• The link varies little by year, except for Labour
  first pref voters
• No difference between more/less candidate centred
  voters

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So what?

• Seems STV can be used to signal coalition
  preferences
• But also can signal other things for which we
  have no codes, particularly on second preferences
• And of course it could be that voters want
  candidates/parties they vote for in government